The present invention relates to video tape recorders. More particularly, the present invention relates to improved techniques for aligning the component parts of a drum assembly that is used in a video tape recorder.
Video tape recorders that employ rotating record/reproduce head assembly are well known. In such recorders, tape that is used as the recording medium is wrapped partially around a drum assembly that houses the rotating record/reproduce head assembly. In general, the head assembly rotates while the tape is moved (or held stationary) so as to record or reproduce. By way of example, FIG. 1 illustrates a video tape recorder 2 that includes a housing 4 for enclosing the components and circuitry of the video recording devices. As shown in the cut away portion 6, one of the components is a drum assembly 10 having a tape 8 wrapped partially therearound. By way of example, representative video tape recorders utilizing a drum assemblies may include models DVW, DNW, HDW Series manufactured by Sony Corporation.
FIGS. 2A and 2B illustrates an exemplary drum assembly 10. FIG. 2A is a perspective view, of the drum assembly 10, and FIG. 2B is a side elevation view, in cross section, of the drum assembly 10. As shown, the drum assembly 10 includes an upper drum 12, an inner drum or scanner 14, a lower drum 16, a drum support 18, a spindle assembly 20, an upper base 22 and a lower base 24. The inner drum 14, which is disposed inside an opening 26 formed in the upper drum 12, is attached to the spindle assembly 20 via four inner drum screws 28. The inner drum 14, among other things, includes a plurality of record/reproduce heads 15 configured for video recording. The record/reproduce heads 15 are disposed between the upper and lower drums 12, 16. As should be appreciated, the record/reproduce heads 15 are rotated via the spindle assembly 20 to accomplish any recording or reproducing tasks. The inner drum 14, also includes a cavity 32 for allowing a slip ring assembly (not shown) to be positioned therein. Slip ring assemblies carry electrical signals between the rotating heads and other equipment with which the rotating head has relative motion. By way of example, representative slip ring assemblies may be found in co-pending patent application Ser. No. 09/721,436, which is titled xe2x80x9cSlip Ring Assembly For Use In a Video Recorderxe2x80x9d and filed on Nov. 22, 2000, and which is herein incorporated by reference.
The lower base 24 is structurally coupled to the upper base 22 and the upper base 22 is structurally coupled to the lower drum 16. The drum support 18 is configured to hold or support the upper drum 12 relative to the lower drum 16. For example, as shown, the drum support 18 includes an upper drum support arm 36 and a lower drum support arm 38 that are attached together via a pair of upper drum support screws 40. Further, the lower drum support arm 38 is attached to a lower surface of the lower drum 16 via a pair of lower drum support screws 42 and the upper drum support arm 36 is attached to an upper surface of the upper drum 12 via a pair of upper drum screws 44. In most cases, the lower drum support arm 38 includes an inner peripheral surface 39, which abuts an outer peripheral surface 13 of the upper drum 12. The inner peripheral surface 39 is typically arranged in an arcuate manner. In order to ensure contact between the lower drum support arm and the upper drum, a leaf spring mechanism 45 for biasing them together may be provided. In addition, the drum support 18 provides a space 30 so as to position a tape (not shown) along the outer periphery of the drum 10 adjacent the recording/reproducing heads 15.
The spindle assembly 20 includes a spindle 46 and a spindle pad 48. The spindle 46 is rotatably coupled to the upper base 22 via a set of bearings 52 and powered by a motor (not shown) housed within the lower base 24. The motor is typically configured to rotate the spindle 46 along an axis 54 at speeds up to 10,000 revolutions per minute (rpm). One end of the spindle pad 48 is attached to the spindle 46 while the opposite end is attached to the inner drum 14. The spindle pad 48 includes a guide post 33 and a mounting flange 50. As shown, the guide post 33 extends into a portion of the cavity 32, and the mounting flange 50 provides a mounting surface for securing the inner drum 14 thereto. Furthermore, the guide post 33 includes a guide hole 34 configured for supporting a slip ring assembly (not shown).
Unfortunately, the design and implementation of the drum assembly leads to problems which may shorten part life and the proper functioning of the video recording device in which it is used. For example, one problem associated with the above assembly is that the component parts (e.g., spindle assembly 20, lower drum 16, upper drum 12) of the drum assembly may become misaligned. As a result of misalignment, excessive vibrations and/or excessive wear may be encountered during rotation of the spindle within the upper and lower drums. In addition, it may be difficult for the heads 15 to record or reproduce.
In view of the foregoing, there are desired improved methods and apparatuses for aligning the component parts of a drum assembly.
The invention relates, in one embodiment, to an indicator tool for checking the alignment of a component of a drum assembly used in a video recording device. The indicator tool includes a housing. The indicator tool further includes a holding mechanism coupled to the housing and adapted to secure the indicator tool to a second component of the drum assembly. The indicator tool also includes a measuring device coupled to the housing and adapted to measure the eccentricity of the component when the indicator tool is secured to the second component of the drum assembly.
The invention relates, in another embodiment, to an alignment tool for aligning a support structure of a drum assembly used in a video recording device. The alignment tool includes an alignment plate adapted to be secured to a component of the drum assembly. The alignment plate includes a reference surface, which provides a reference position relative to the position of the component of the drum assembly when the alignment plate is secured to the component of the drum assembly. The alignment tool also includes a positioning mechanism coupled to the alignment plate and adapted to adjust the position of the support structure so that the support structure abuts the reference surface of the alignment plate. When the support structure abuts the reference surface, the support structure is placed in the reference position relative to the position of the component.
The invention relates, in another embodiment, to an alignment fixture for aligning a component of a drum assembly used in a video recording device. The alignment fixture allows the drum assembly to be aligned outside of the video recording device. The alignment fixture includes a base configured to receive and support the drum assembly. The alignment fixture further includes a reference system configured to place a portion of the drum assembly in a known position relative to the base. The alignment fixture further includes a positioning system for adjusting the position of the component of the drum assembly relative to the base when the portion of the drum assembly is positioned in the known position.
The invention relates, in another embodiment, to a method of aligning a drum assembly used in a video recording device. The method includes checking the alignment of a first component of the drum assembly relative to an axis of the drum assembly. The method further includes making a determination as to whether the alignment is within a desired limit. The method also includes adjusting the position of the first component relative to the axis when the alignment is not within the desired limit. The adjusting placing the alignment within the desired limits.